Mats to keep feet clean generally are designed for household use, that is, the mat is large, relatively stiff, and has clearly marked top and bottom sides because the bottom side will remain permanently downward.
Taking such mats camping, skiing, skating, hiking and so on is not remotely convenient. While a skier at the slope or lift needs to put on ski boots or skis, lugging around a stiff rolled up mat is a bulky nuisance and a quick way to kill the pleasure of outdoor athletics.
In addition, note that when a non-folding household type mat is rolled up (since most household mats are too stiff to fold), necessarily the dirty bottom side of the mat (which rested on the ground) is rolled up against a clean portion of the top side of the mat. This instantly transfers dirt from the bottom to the top. If the user attempts to use the mat a second time, they will find the formerly clean upper surface has become dirty during the period of storage (rolled up) due to the dirty side contacting the clean side.
Thus for all these reasons, household mats are not really useful, nor applicable to, athletic mats for outdoor usage.
Folding mats may be used in the outdoor context but in general folding mats may be so very light in weight—small tarps more than mats/pads—that they tend to stick to the bottom of the foot, to footwear, equipment, and so on, or just blow away in a breeze. Folding mats made of more sturdy material would be desirable, but would still leave a frustrating problem. In general, a mat will be placed on the ground or snow and then stepped on, thus grinding dirt, mud, snow, ice or the like into the bottom of the mat. When the ordinary style of mat is folded, all this clinging dirt then transfers itself from the bottom/dirty side to adjacent (after folding) parts of the top side, unless the mat is one of the designs which aim to prevent this. Thus, the folding mat is usable for clean feet exactly once, after which the act of folding it transfers dirt to the previously clean side. The second time the mat is unfolded, the top surface is already dirty.
Another challenge with such traditional style mats that do not attempt to solve these problems is that the user will get their hands dirty while folding the mat together, one hand on a clean portion and one hand on a dirty portion, since it is impossible to fold a mat without placing the fingers around one edge or another. Worse, the dirty side will be partially exposed and will immediately begin donating the dirt if picked up off the ground to the environs: the user's hands during casual contact, the car seat, the shelf, etc. It would obviously be preferable to provide a mat with one-handed folding characteristics.
Foldable mats have been known. In general such mats comprise foam core materials with a very thin material on the top and bottom, which is then molded together in a manufacturing process which is very specific to foam only.
Attempts have been made to provide folding mats which address such issues. U.S. Pat. No. 9,161,641 to Wentland on Oct. 20, 2015 teaches a foldable foam-type mat in which a single cushioning material has been grooved in certain places to allow folding.
Fairly simply, the '641 reference teaches two folds. This may also be found in such real world-products as the “Qwick Stand” mat. (www.qwickstand.com) The foam construction means that the mat is thick and quickly gets thicker as the thickness doubles with each fold. Fairly bulky yoga mats such as the Yofo mat (www.khataland.com) also feature a foam sandwich construction and also become quite bulky quite quickly as the folds double the thickness repeatedly.
U.S. Pat. No. 5,051,293 to Breitscheidel et al on Sep. 24, 1991 teaches a foldable foam mat which, like Wentland, has a single unibody construction of the cushioning material with grooves or depressions across it. There appears to be no substrate to hold discontinuous panels together. Unlike Wentland, the '293 patent does show that the grooves may be of different types: single grooves versus double grooves, thus encouraging double-folding. However, there is no indication that a formula for groove width may be applied, no indication of a substrate, etc etc.
All such mats essentially require two handed folding involving picking up the mat and manipulating it two handed.
It is worth noting that some of these mats do achieve a “dirty-side to dirty-side” fold by starting with a counter-intuitive “book fold”: a type of fold in which the fold line is raised up so that the areas on each side collapse together under it, rather like an open book resting face-down on a table closes when it is lifted up by the spine. However, most people think in terms of picking up an edge or corner and folding it over, not in reaching for a central fold-line and lifting it up while allowing the edges to drag across the ground toward the middle.
It would be preferable to provide a mat which is portable by being dramatically more compact in folded states and yet which maintains a top surface which is clean, with no transfer of dirty from the bottom to the top surface during storage.
It would be preferable as well to provide a mat which then remains folded without the use of ties or the like, by avoiding the use of foam material in the hinges, and the use of a flexible hinge material.
It would further be preferable to provide a mat which easily folds into a small and thinner package. This further would allow storing in a small bag as a compact package rather than as a large bundle. Folded down smaller, it becomes more useful for other scenarios as well, fitting into car cargo nets, handbags, glove boxes, smaller backpacks and so on.
It would further be preferable to provide a mat which can be made in either of two ways: either with a flexible base layer with attached panels of hard material or in a single material unibody construction molded of a single material without a substrate.
It would further be preferable to provide a mat with easy one handed folding and unfolding methods of use. It would even further be preferable to provide a mat with an easy to use hand grip/hand hold to not just allow the user to fold it one handed but to furthermore automatically start the user into the proper fold sequence.
It would yet further be preferable to provide a mat which may be reused over and over again without cleaning, due to the top surface remaining clean and out of contact with the bottom surface.
It would further be preferable to provide a mat which uses the beneficial properties of rubber, EPDM rubber (ethylene propylene diene monomer (M-class) synthetic rubber), neoprene or similar harder materials which for a given thickness provide enhanced comfort, and durability. It would further be preferable to use these materials which are water-proof rather than merely water resistant (most foams are only water-resistant and can be difficult to clean when saturated and can take a surprising amount of time to dry).
It would further be preferable to provide a mat for which a bottom surface tread pattern may be used to increase traction on snow, ice, mud and similar surfaces.
It would yet further be preferable to have a thinner, denser mat so that when laid out it is less susceptible to wind, as foam mats, being very light, low density, and high profile, blow away extremely easily.